There is increasing interest in providing telecommunications services over packet networks that were formerly provided over TDM (time division multiplexed) networks. Most of these telecommunications services require a synchronized clock, which is not provided by the physical layer of a packet network in the same way as it was provided by the physical layer of the TDM network. Various approaches to synchronization over packet networks have been proposed and standardized (see NTP and IEEE Std 1588, among others), but these methods usually distribute a single time-of-day reference. This is not a good match for some services which formerly ran over plesiochronous TDM network connections, where each connection was allowed a certain frequency inaccuracy, hence multiple connections entailed multiple reference clocks. For the sake of backwards compatibility, it is desirable for this possibility of multiple reference clocks to be supported over packet networks. A brute-force approach to this issue is to use adaptive clock recovery, which tries to average out packet rates to calculate the bit clock. Adaptive clock recovery tends to have poor wander performance, even when timestamping and packet sequence numbering are used to overcome packet-loss issues.